JPH11293686A - Pile arrangement structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce stress of piles at an earthquake by arranging shearing force bearing piles only supporting horizontal force on the further outside of piles corresponding to the outer circumferential corner parts of an upper structure within a pile group transmitting force to the ground. SOLUTION: The weight of an upper building 1 is supported with a pile 3 group through a foundation 2. When the piles 3 are arranged in this way, maximum shearing stress is generated in the piles 3a on the four corners by horizontal force at an earthquake. For reducing the stress, shearing force bearing pipes 4 supporting only horizontal force are arranged outside the piles 3a. Since the piles 4 are deformed to absorb earthquake energy at a big earthquake, the piles 4 function as energy absorbing piles. Accordingly, damage of the other pile 3 group is restrained to minimum. Particularly, even if the piles 4 are deformed by a big earthquake, influence on the supporting performance of the building can be minimized, and increase of cost can be restrained to minimum.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pile arrangement capable of reducing the stress generated in a pile during an earthquake.

[0002]

2. Description of the Related Art Generally, a building (superstructure) is supported by a large number of piles via a foundation, and the piles are arranged vertically and horizontally at intervals with respect to the ground. In a rectangular building in plan view, piles are arranged vertically and horizontally corresponding to the building plane, and all piles support the load of the building.

[0003] By the way, the stress generated in the pile during the earthquake includes a stress generated by a shear force (horizontal force) applied from an upper building (upper structure) and a stress generated by deformation of the ground itself. . Among them, it is known that the stress generated by the horizontal force applied from the upper building is the largest at the four corner piles among the many piles. Since a larger additional axial force is applied to the piles, as a result, the piles at the four corners are often damaged during an earthquake.

[0004]

As described above, conventionally, it is known that the piles at the four corners supporting a building are often damaged by an earthquake, but at present, the cost is not increased so much. However, there is no technology for effectively reducing the stress of piles during earthquakes.

The present invention has been made in view of the above circumstances, and has as its object to provide a pile arrangement structure capable of effectively reducing the stress of a pile during an earthquake without increasing the cost burden.

[0006]

According to the present invention, a pile group for transmitting a load of an upper structure to the ground via a foundation is mainly provided outside a pile corresponding to an outer peripheral corner of the upper structure. A shear-bearing pile that supports only horizontal force is provided.

In the case of this structure, the shear load bearing pile arranged at the outermost peripheral portion bears the most horizontal force applied from the upper structure. The shear stress of the pile corresponding to the outer peripheral corner of the upper structure can be reduced. Also, during a major earthquake,
Since the shear force bearing pile functions as an energy absorbing pile and absorbs seismic energy by deforming itself, damage to other pile groups can be minimized. In particular, in this case, the shear load bearing pile is not provided to support the weight of the superstructure itself, and the weight of the superstructure is supported by other pile groups, so the pile supports the superstructure. There is no loss in performance.

A second aspect of the present invention is characterized in that, in the first aspect, the shearing force bearing pile is vertically insulated when the superstructure is constructed, and is connected when the construction is completed.

In this structure, since the shear load bearing pile is constructed so as not to bear the weight of the upper structure, the horizontal force applied from the upper structure and the additional axial force at the time of the earthquake can be borne most. . And because the weight of the superstructure itself is not borne, even if it is deformed during a large earthquake,
There is almost no effect on the support performance of the superstructure.

According to a third aspect of the present invention, in the first or second aspect, the upper structure has a substantially rectangular shape in a plane, and the shear force-carrying pile is disposed further outside a pile corresponding to four corners thereof. Features.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an arrangement structure of a pile according to an embodiment, where (a) is a side view and (b) is Ib-Ib of (a).
It is arrow sectional drawing.

In this structure, the weight of an upper building (upper structure) 1 having a rectangular plane is weighted by twelve piles 3 arranged in multiple rows and columns (3 × 4 rows) via a rectangular plate-shaped foundation 2. Supported by groups. With this arrangement of the piles 3, the largest shear stress is generated in the piles 3a at the four corners (outer peripheral corners) due to the horizontal force at the time of the earthquake. Therefore, in order to alleviate this, a shear force bearing pile 4 mainly supporting only horizontal force is arranged further outside the four corner piles 3a.

In this case, the shear force bearing pile 4 is shown in FIG.
As shown in (a), at the time of construction, a reinforcing bar 4a of the pile head is simply inserted into the opening 6 of the foundation 2 in order to insulate the adhesion in the vertical direction.
As shown in FIG. 2 (b), the opening 6 is filled with concrete 7 to be integrated with the foundation 2. Therefore, the shear force bearing pile 4 does not bear the weight of the upper building 1, but can bear mainly the horizontal force. Therefore, at the time of an earthquake, the horizontal force and the additional axial force applied from the building 1 can be borne most.

According to this structure, since the shearing force bearing pile 4 located at the outermost periphery bears the most horizontal force applied from the upper building 1, the four corners located inside thereof are correspondingly increased. The shear stress of the pile 3a can be reduced. Similarly, the shear stress of the entire group of piles 3 can be reduced. Further, since the additional axial force during an earthquake can be borne most, the load on the other piles 3 during the earthquake can be reduced.

In the event of a large earthquake, the shear force-carrying pile 4 located at the outermost periphery is deformed (including destruction), thereby absorbing seismic energy. As a result, the damage to the other three groups of piles can be minimized.
In particular, since the shear load bearing pile 4 does not support the weight of the building 1 itself, even if it is deformed by a large earthquake, the influence on the support performance of the building is small.

Next, a brief description will be given of the result of analyzing the load shearing force of a pile using a three-dimensional thin-layer method. As shown in FIG. 3, the model used for the analysis has a structure in which the length from the foundation 2 to the ground H1 = 15 m, the embedding depth H2 = 2 m, and four shear force bearing piles 4 exist. (A), (b)
As shown in the figure, when there are 16 main piles 3 (pile spacing 6
m, 12 m) and 64 cases (pile spacing 6 m), the pile head was forcibly deformed by 1 m and the shear force of each pile was examined. Normal pile head displacement is about 1cm, so 1cm
The shear force at the time was compared. Further, since the shear force per one of the main piles 3 is reduced due to the presence of the shear force-carrying piles 4, the comparison was made using the shear force corrected by the ratio of the number of the piles.

As a result, in the case of 16 piles and a pile spacing of 6 m, the shear force of the pile 3a at the four regular corners was reduced to 83%, and the shear force of the other piles was reduced from 90% to 95%.
In other cases, the shearing force of the piles 3a at the four regular corners was reduced to about 90%, and the shearing force of other piles was also reduced to about 95%. In addition, as a general tendency, it was found that the smaller the number of piles and the narrower the interval between the piles, the higher the effect of providing the shear force bearing piles 4. That is, the shear load bearing pile 4
It was found that the effect of reducing the shearing force of the entire pile was more than the number of piles increased by four.

It is known that the largest load is applied to the piles at the outer peripheral corners of the building other than the rectangular plane in the event of an earthquake. Similar effects can be obtained.

Further, in the above embodiment, the shear force-carrying piles 4 are arranged one at each corner, but a plurality of them may be arranged.

[0020]

As described above, according to the first aspect of the present invention, of the pile group for transmitting the load of the superstructure to the ground via the foundation, the pile corresponding to the outer peripheral corner of the superstructure is used. Further, since the shear force-carrying pile is arranged on the outside, the shear stress of the pile at the outer peripheral corner can be reduced. Further, at the time of a large earthquake, the shear force bearing pile functions as an energy absorbing pile, so that damage to other pile groups can be minimized. Further, even if the shear load bearing pile is deformed in such a manner, the shear load bearing pile is not intended to support the weight itself of the upper structure, so that the pile support performance of the upper structure is not impaired. In this case, the above effects can be expected only by arranging a suitable number of shear force bearing piles at the outermost peripheral portion, so that an increase in cost can be minimized.

According to the second aspect of the present invention, the shear force bearing pile and the foundation are connected for the first time upon completion of the construction, and the shear force bearing pile does not bear the weight of the upper structure. The shear force-carrying pile can bear the horizontal force applied from the object and the additional axial force during an earthquake. Therefore, even if the shearing load-carrying pile is deformed during a large earthquake, the support performance of the upper structure is hardly affected.

According to the third aspect of the present invention, the effect of the first or second aspect can be obtained by arranging the shear load bearing pile outside the four corner piles of the upper structure.

[Brief description of the drawings]

1A and 1B show a configuration of an embodiment of the present invention, wherein FIG. 1A is a side view, and FIG. 1B is a cross-sectional view taken along the line Ib-Ib in FIG.

FIG. 2 is a diagram for explaining the timing of connection between the shear load bearing pile and the foundation in the same embodiment,
(A) is a state at the time of construction, (b) is sectional drawing which shows the state at the time of completion of construction.

FIG. 3 is a side view of a model used for verifying an effect provided by providing the shear force bearing pile.

FIG. 4 shows an example of a pile arrangement (a) in the model of FIG. 3,
It is a top view which each shows (b).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper building (superstructure) 2 Foundation 3 Pile 3a Four corner pile 4 Shear load bearing pile

Claims (3)

[Claims] 1. A shear force-carrying pile mainly supporting only a horizontal force is further provided outside a pile corresponding to an outer peripheral corner of an upper structure in a group of piles for transmitting a load of the upper structure to the ground via a foundation. Pile arrangement structure characterized by being arranged. 2. The pile arrangement structure according to claim 1, wherein the shear force bearing pile is vertically insulated when the superstructure is constructed, and is connected when the construction is completed. 3. The pile according to claim 1, wherein the upper structure has a substantially rectangular shape in a plane, and the shear force-carrying pile is further disposed outside a pile corresponding to four corners thereof. Arrangement structure.